Internal valve-gear for steam-engines



J. A. LE CAIN. INTERNAL VALVE GEAR FOR STEAM ENGINES. APPLICATION man JUNE 17, 1919.

2 SHEETS-SHEET a N MA N M w n N N u, L 1 3% N N x K PatentdSepf. 13,1921.

J. A. LE CAIN. INTERNAL VALVE GEAR FOR STEAM ENGINES.

APPLICATION FILED JUNE 17, [919.

Z3 ZZ Z Z UNITED STATES PATENT OFFICE.

JOHN A. LE CAIN, F MALDElN', MASSACHUSETTS.

INTERNAL VALVE-GEAR FORL STEAM-ENGINES. I

Application ,flled June 17,

To all whom it may concern:

Be it known that I, JOHN A. LE CAIN, a citizen of the United States, residing at Malden, in the county of Middlesex and State of Massachusetts, have invented certain new and useful Improvements in Internal Valve- Gears for Steam Engines; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to valve gear for fluid pressure engines and more particu larly to internal valve gear for steam pumping engines in which a pressure actuated main valve governing the distribution of steam to opposite sides of the working pistion-is controlled by a pressure actuated auxiliary valve or valves.

The objectof the invention is to provide certain improvements in the construction and mode of operation of internal valve gear for fluid pressure engines tending to increase the efficiency and reliability thereof by drawings, in which: Figure '1 is a view in longitudinal section of the device; Fig. 2 is a transversesectional view thereof taken on the line 2-2 of Fig. 1; Fig. 3 is a fragmentary top plan view thereof; Fi 4 is a dia rammatic view in which the main steam cylinder and the auxiliary cylinder are arranged axially in the same plane rather than in planes at right an les to each other as actuallyconstructed; ig. 5 is a top plan view of the slide valve and slide valve seat indicating the relation thereto of certain of the steam passages shown in Fig. 4; Fig. 6 is 'a diagrammatic view similar to Fig. 4 showing the slide valveand one of the auxiliary valves in difierent position; Fig. 7 is a ium View similar to Fig. 5 with the slide ve in the position shown in Fig. 6; and Fig. 8 is a detail sectional view taken through one of the grooves in the slide valve and Specification of Letters Patent. Y Patnted Sept. 13, 1921.

1919. Serial no. 304,782.

illustrating the relation thereto of certain of the passages when the valve is in its extreme position toward the right.-

As shown in the drawings, the main steam cylinder 10 is fitted with a properly packed piston 11 which is secured to a piston rod 12, the-outer end of which may be secured to a pump piston, or otherwise suitably connected in accordance with .the work to beperformed. The cylinder 10 is provided with the usual exhaust passage 13 and ports 14 and 15 which serve alternately and sev erally as induction and exhaust ports ac-;

cording to the direction of movement of the piston. The ports 14 andlo open into the cylinder 10 at oints a little distant from the ends thereot and are extended to the extreme ends of the cylinder by starting ports 16 and 17, respectively, of smaller area, which serve alternatel to admit steam behind the piston 11, w en the outlet of the adjacent main port 14 orv 15' -,is covered thereby, so as to start the piston gently in a reverse direction. A steam-chest 18 is secured upon the side of the cylinder 10 and'receives steam through a supply pase sage 19 in the main cylinder casting. The

steam-chest 18 incloses a valve seat 20 upon which a slide valve 21 is adapted to recip;

rocate to govern the admission and exhaust of steam to and from the main steam cylinder 10, on opposite sides of-the'pistonll, by connecting the steam-chest 18 and the exhau'st passage 13 alternately with one or the other of the ports 14 and 15 in the usual manner. The slide valve 21 is carried by the reduced'central portion of a plunger 22 the opposite ends of which reciprocate in auxiliary cylinders 24 and 25 formed at 0pposite ends of the steam-chest 18; Equal pressures are normally exerted against the opposite ends of the plunger 22 that is ex-' cept when the valve is to be moved so that it is maintained in any position to which it is moved; The reciprocation of the plunger 22 is due to unbalanced pressures at oppo' site ends thereof caused by alternately shutting off the steam supply to the cylinders 24 and 25 and simultaneously opening said cylinders to exhaust.

The admission and exhaust of steam to the cylinders 24 and 25 is controlled by two auxiliary valves 26 and 27 each of which is mounted to reciprocate in sockets formed in an auxiliary valve chest or casing 28, the

valve ca ings-28 being secured to opposite ends of the steam-chest 18. Each auxiliary valve is formed with an enlarged head 29 at the top and a reduced portion 30 near the lower end thereof. The two cylinders 24 and 25' are severally connected by an inlet port 31 with the interior of the adjacent auxiliary valve casing, which is in turn connected by an inlet passage 32 with the steam-chest 18. Each of the cylinders 24 and 25 is also connected with the interior of the adjacent auxiliary valve casing by means of an exhaust port 33, and the in terior of said casing is'connected by a passage 34 with the main exhaust passage 13.

tion of the valve, and the port 31, while communication is obstructed between the exhaust port 33 and the passage 34, thus preventing the pressure in said cylinder from being exhausted. When, however, the auxiJiary valve is raised to operative position, as illustrated by the position of the valve 27 in F igQ 6, the inlet port 31 and the inlet passage 32 are disconnected, thus shutting off the supply of steam to \the cylinder 25 while communication is established between the exhaust-port 33 and the passage 34, through the annular space 35, thus exhausting the steam from said cylinder. The

I which shutting off of the supply of steam to the cylinders 24 and 25 while the pressure there- -m is permitted to exhaust, insures quick action of the slide valve and prevents waste of steam. In order that the plunger 22may be prevented from striking the closed ends of the cylinders 24 and 25, each exhaust, port 33 opens into its respective cylinder at such a point that-the port will be .elosed by the plunger 22 before ,the plunger reaches the end of its stroke. The steam thus trapped in the auxiliary cylinder provides a cushion revents the plunger from striking the cylinder head and causing the plunger to be reversed without shock.

The auxiliary valves are raised into operative positions by the admission of steam from the main steam cylinder 10 to an annular, space 37 formed in the interior of each auxiliary valve casing beneath the head 29 of the valve. In order that the valve 27 may be actuated to effect the shifting of the ,slide valve and the reversal of the piston 11 after its movement toward the left, a

passage 38 extends downwardly from the space 37 beneath the head of the valve and terminates in a flaring port 39 1n the shde valve seat 20, adjacent the upper end of a passage 40 which leads downwardly from the valve seat and opens at 41 and 42 into the main cylinder 10. A groove 43 in the under face of the slide valve 21 is adapted, when the slide valve is at its extreme positign toward the left, as indicated in Fig. 4, to cooperate with the valve seat terminals of the passages 38 and 40, so as to establish communication between the valve 2? and the cylinder 10. Live steam from the right side of the piston 11 thus gains access through the port- 41, the passage 40, the groove 43 and the passage 38 to the annular space 37 and quickly raises the valve 27. The port 41 is located at such a distance from the nearer end of the cylinder 10 that the piston 11 may pass beyond said port just before coming to the end of its stroke and the extension of the passage 40, terminating in the port 42, is of greater cross sectional area than the rest of the passage and serves to prevent short stroking of the piston 11 at that end of the cylinder, in the usual manner.

The raising of the valve 27 imbalances the pressures upon opposite ends of the plunger 22 by causing the pressure to be exhausted from the cylinder 25, and the plunger 22 immediately moves to the right until it is cushioned and arrested by the steam which is trapped in said cylinder after the plunger 22 has closed the exhaust port 33. By this time the slide valve has been shifted so as to connect the right side of the main cylinder 10 with the exhaust and to admit steam at normal pressure to the passage 14. The steam enters the cylinder 10 through the starting passage 16, which opens into the cylinder 10 at the extreme left end thereof so that communication with the cylinder 10 through the starting passage is never shut off by the piston 11. I The steam thus entering the c linder 10 first cushions the movement of t e piston 11 toward the left, preventing it from striking the end of the cylinder and then gently starts the piston in the opposite direction.

After the auxiliary valve 27 has been raised, as indicated in Fig. 6, by the admission of steam to the annular space 37, to effect the arrest and reversal of the piston 11, the pressure in the space 37 is permitted to exhaust and at the same time pressure is applied to the top and bottom of the valve 27 to positively return the valve to normal position, the valve being forced downwardly by the excess of pressure above the head 2-) the top surface of which is of greater area than the surface which receives the pressure at the bottom of the valve. To this end, the shifting of the slide valve to the right brings the groove 43 into position to connect the passage 38, with an extension of the passage 15 leading to the exhaust passage 13 the passage 38 and the groove 43, to permit exhaust of pressure from the space 37 by means of the flaring port 39 Fig. 8). At the same time the opening of t e passage 14 to live steam causes steam to pass therefrom through the passage 45 and ports 46 and 47 to the top and bottom, respectively, of the valve 27. The passage of steam from the port 46 to the top of the valve is facilitated by the provision of an annular groove 48 *ig. 2) in the head 29 which is opposite the port 46 when the valve is in raised position. Steam gains access to the top sur face of the head 29 by working upwardly from the groove 48 around the side of the head to the to reason of the di erence in area between the top and bottom surfaces of the valve, the valve is positively and gently forced down to its normal, position, as soon as permitted by the release of pressure from the annular space 37. Positive pressure at the top and bottom of the valve holds it in normal position at the start of the movement toward the left of the plunger 22. As said movement progresses and the slide valve connects the passage 14 with the exhaust, this pressure is permitted to exhaust through the passage 45. In order to prevent any steam which may possibly leak downwardly from the annular space 35 from reaching the lower extremity of the valve and raising the valve by building up pressure beneath it, an annular groove 49 2) is provided near the bottom of the valve. WVhen the valve is in its lower position this groove 49 is opposite "the port 47 and the downwardly leaking steam is trapped in the groove and passes to exhaust through the passage 45.

Inasmuch as high pressure is utilized for moving the auxiliary valve 27 in both directions it is very important that suitable provision be made for preventing the valve from striking the valve casing at the end of each of its movements. It" will be seen that with the present construction the operative or upward movement of the valve is cushioned by the exhaust steam that is confined in the chamber above the head 29 after the exhaust from this chamber is shut oil by the risin of the head above the port 46. The cushion thus provided is amply effective for its purpose by reason of the greater area of surface exposed to the steam as it is compressed in the chamber above the head 29 than the area on the under side of the head which is acted upon by the high pressure steam which raised the valve. The return or downward movement of the valve is cushioned by live steam that is supplied to the chamber below the bottom of the valve.

The auxiliary valve 26 is connected with the main cylinder 10 and with the exhaust passage 13 by means of a series of passages which are identical in formation and arsurface thereof and by rangement with the passages connected with the auxiliary valve 27 for the same purpose. Steam is supplied to theann'ular space 37 beneath the head of the valve 26 by means of a passage 50 extending downwardly therefrom and terminating in a flaring port 51 in the slide valve seat 20 adjacent the extension 52 of a. passage 53 extending downwardly from the slide valve seat 20 and opening at 54 and 55.into the main cylinder 10. A groove 56 in the under face of the slide valve 21 cooperates with the valve seat terminals of the passage 50 and 53 when the slide valve is at its extreme position toward the right to permit live steam to pass from the cylinder 10 at the right side of the piston 11 to the space 3?. Steam is supplied to the top and bottom of the valve 26 by means of a passage 57 leading from the passage 15 and communicating with the interior of the valve through ports 58 and 59. hen the working piston 11 in moving toward the right has passed beyond the port 54 the auxiliary valve 26 is operated in the same manner as has been described in connection with the valve 27 to shift the slide valve and effect the arrest and reversal of the pistonll.

The operation of the improved valve gear is as follows: \Yhen the working piston 11 reaches the position shown in Fig. 6, the port 41 is uncovered, permitting steam at normal pressure to flow through the passage 40, the groove 43 in the slide valve, and the passage 38 to the annular space 37 beneath the head of the auxiliary valve 27, quickly raising the valve. As the valve rises, communication between the passages 32 and 31 is interrupted, thus shutting oil the supply of steam to the cylinder 25. while 7 communication is established between the exhaust port 33 and the passage 34, through the annular space 35, permitting exhaust of steam from said cylinder and unbalaneing the pressures on the plunger 22. This causes immediate movement of the plunger 22 and the slide valve toward the right. shutting off the supply of steam to the right side of the main cylinder 10 through the passage 15 and connecting said passage with the ex haust, and also permitting the inlet of steam to the cylinder 10 at the left of the piston 11 through the passage 14 and the starting passage 16, thus arresting and reversing the piston 11. The movement of the slide valve to the right disconnected the passage 38 and 40, shutting off the supply of steam to the annular space 37 beneath the head of the auxiliary valve 27 and connecting said space 37 and passage 38 with the exhaust through the groove 43 in the slide valve, the extension 45 and the passage 15 as shown in Fig. 8. The steam from the passage 14 now has access to the top and bottom of the auxiliary valve 27 through the passage 45 top and bottom of the and ports 46 and 47. A greater area being subjected to pressure at the top than at the bottom of the valve 27, the valve is forced downwardly as fast as the pressure beneath the head 29 is permitted to exhaust.

As the slide valve starts to move toward the right, the auxiliary valve 26 is held positively in its lower or normal position by the unequal pressures at the top and bottom thereof produced by steam vconveyed from the "right end of the cylinder 10 through the passages 15 and 57 and ports 58 and 59. During the movement of the slide valve, however, the pressures at the auxiliary valve and the pressure in the annular space 37, all become equalized, the pressure at the top and bottom of the auxiliary valve being relieved through the passage 57 upon the connecting of the passage 15 with the exhaust passage becomes connected with the exhaust through the passage 50, the groove 56 and the pas sage 53. Thus the auxiliary valve I 26 is ready to be quickly raised to again reverse the slide valve, as soon as the piston 11 has passed beyond the port 54, whereupon the piston 11 will be arrested and reversed in the same manner as at the left end of the cylinder 10.;

t will be seen that a simple and compact form of auxiliary valve has been provided which may be positively and quickly moved into operative position by the direct application thereto of live steam from the main cylinder', which may be positively returned to normal .position in a like manner, and that provision has been made for effectively cushioning the movements of the valve in both directions so as to avoid damage due to the striking of the valve against the valve casing.

lVhile it is preferred to mount the auxiliary valves to reciprocate vertically, and otherwise to employ the specific construction and arrangement of parts shown and described, it will be understood that such construction and arrangement is not essential, except so far as specified in the claims and may be changed or modified without departing from the broader features of the invention. a

The invention having been described, what is claimed is l. A fluid pressure engine comprising a main steam cylinder, a slide-valve, a connected valve-plunger, two separate and independently operable auxiliary valves each controlling the inlet and exhaust of steam at one end respectively of the plunger, and means controlled by the slide-valve for controlling the movements of the auxiliary valves and the inlet and exhaust of steam to and from the main cylinder.

2. A fluid pressure engine comprising a 13 and the space 37 also auxiliary valves at predetermined intervals controlled by the movements of the main slide valve.

3. A fluid pressure engine comprising a main steam cylinder having induction and exhaust passages, a slide-valve with its valve plunger for controlling the admission and exhaust of steam to and from the passages, separate and independently operable auxiliary valves for controlling the movements of the slide-valve, inlet and exhaust steam passages for the auxiliary valves, and means controlled by the slidevalve for connecting the auxiliary valve passages with the main induction and exhaust passages at predetermined intervals to control the movements of the auxiliary valves thereby.

4. A fluid pressure engine comprising a main steam cylinder having induction and exhaust passages, a piston reciprocating within the cylinder, a main valve with 1ts valve plunger adapted to distribute fluid under pressure to opposite ends of the steam cylinder, separate and independent auxiliary valves for controlling the movements of the main valve, and means for imparting movements in opposite directions to the auxiliary valves and to cushion the movements of the auxiliary valves at opposite ends of the stroke.

5. A fluid pressure engine comprising a main valve plunger, two separate auxiliary valves, means controlled by said auxiliary valves for admitting live steam to normally maintain live steam pressure upon opposite ends of the plunger, means controlled by each of the auxiliary valves for momentarily relieving the steam pressure 111301110116 end of the plunger and means for cushioning the resultant movement of the plunger due to the unbalanced pressure.

6. A fluid pressure engine comprising a main steam cylinder, a piston traveling within the cyllnder, a main valve plunger reciprocating transversely'of the axis of th 7; A fluid pressure engine comprising a main valve with its valve plunger, means for normally maintaining steam pressure upon opposite ends ofthe plunger, separate and independent auxiliary valves for controlling the movements of the plunger, means for exerting a pressure in onedirection only upon each auxiliary valve to cause its working stroke, and means for exerting oppositely-directed unbalanced pressures upon each auxiliary valve to return it to initial position. I

8. A fluid pressure engine comprising a main steam cylinder, a piston reciprocating within the cylinder, steam passa es communicating with opposite ends of-t e cylinder, a main valve with its valve plunger controlling the inlet and exhaust of steam to and from the passages, two separate and independently operable auxiliar valves for controllin the movements 0 the main valve, an connections between the steam cylinder and auxiliary valves controlled by the main valve for operating the latter in accordance with the position of the piston.

9. A fluid pressure engine comprising a main valve plunger, means for normally I maintaining steam pressure upon opposite ends of the plunger, a vertically movable auxiliary valve adapted to momentarily relieve the pressure upon one end of the plunger, means for rapidly elevating the auxiliary valve to relieve the pressure and means for exerting oppositely directed unbalanced pressures upon the auxiliary'valve for returning'it to initial position at a relatively slower speed.

10. A fluid pressure engine comprising a I main steam valve and a pilot-valve for controlling the movements of the main steam valve having two portions each of cylindrical form and of unequal diameter forming a shoulder between its ends, and means controlled by the main slide-valve for admitting steam pressure behind the shoulder connecting the two cylindrical portions to move the valve in one direction and for admitting steam pressure to opposite ends of the pilotvalve for moving the latter in the opposite direction.

11. A fluid pressure engine comprising a main steam cylinder having induction and exhaust passages, a piston operating therein, a valve casing arranged transversely of the steam cylinder, a slide-valve reciprocating in the casing, separate and independent pilot-valves reciprocating vertically in the casing at opposite ends of the slide-valve, and steam passages for governing the movements of the pilot-valves controlled. by the position of the main slide-valve.

JOHN A. LE CAIN. 

